much more resorbed than the anterior area which still contains alveolar bone. The anterior grooves therefore, bring the supporting struts closer to basal bone allowing an immediate subperiosteal implant to be accomplished. Sometimes these struts can be placed in an untouched area in between areas of alveolectomies or tooth extractions, allowing the implant to be done immediately. Also the supporting struts can be made to go directly to the base of open sockets. Sometimes it is necessary to wait from 6 months to a year for complete bone regeneration.

Knowing that there is a minute amount of bone resorption by merely reflecting the periosteal tissues away from the bone should make the implantologist extremely cautious regarding any unnecessary alveoplasty.

Since a fixed prosthesis rather than a removable one is the prosthesis of choice in most situations we must maintain as much bone as possible. Naturally replacing the lost bone with a removable conventional denture esthetically can hide many unnecessary evils such as resorption of the hard structures immediately after the teeth are removed. The resorption which continues throughout the life of the patient makes the periodic relining of the dentures necessary. We must reduce a knife-edge ridge in order to widen the ridge so that an implant may be inserted.

Whether or not we remove the excess mucoperiosteal tissue that still remains has to do with the overall esthetics. For ex-ample, how much was the intermaxillary space increased after the bone resorption? Does the maxillary ridge line up properly with the ridge of the mandible or is it in a severe class III position, etc?

Always try to envision making the groove in a knife-edge ridge slightly more toward the lingual side since the inner cortical plate is thicker than the outer one and thus the blade has more bone flanking it buccally or labially where it is needed. Since the maxillary arch becomes narrower as it resorbs, it often causes a cross-bite relationship with the lower resorbed arch which does not become narrower. Placing lower blades lingually often eliminates a class III relationship. Whereas when conventional dentures are done for these cases necessitating surgery in the mandible in order to prevent a cross-bite relationship, this is unnecessary with implants since the blades in the mandible can be placed along the lingual regions (so long as the posterior lingual areas are convex) to eliminate the crossbite caused by the narrowing of the maxillary arch.

Because the prosthesis over the implants is not tissue borne

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